summaryrefslogtreecommitdiffstats
path: root/drivers/cpufreq/elanfreq.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/cpufreq/elanfreq.c')
-rw-r--r--drivers/cpufreq/elanfreq.c228
1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/cpufreq/elanfreq.c b/drivers/cpufreq/elanfreq.c
new file mode 100644
index 0000000000..4ce5eb35dc
--- /dev/null
+++ b/drivers/cpufreq/elanfreq.c
@@ -0,0 +1,228 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * elanfreq: cpufreq driver for the AMD ELAN family
+ *
+ * (c) Copyright 2002 Robert Schwebel <r.schwebel@pengutronix.de>
+ *
+ * Parts of this code are (c) Sven Geggus <sven@geggus.net>
+ *
+ * All Rights Reserved.
+ *
+ * 2002-02-13: - initial revision for 2.4.18-pre9 by Robert Schwebel
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+#include <linux/delay.h>
+#include <linux/cpufreq.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/msr.h>
+#include <linux/timex.h>
+#include <linux/io.h>
+
+#define REG_CSCIR 0x22 /* Chip Setup and Control Index Register */
+#define REG_CSCDR 0x23 /* Chip Setup and Control Data Register */
+
+/* Module parameter */
+static int max_freq;
+
+struct s_elan_multiplier {
+ int clock; /* frequency in kHz */
+ int val40h; /* PMU Force Mode register */
+ int val80h; /* CPU Clock Speed Register */
+};
+
+/*
+ * It is important that the frequencies
+ * are listed in ascending order here!
+ */
+static struct s_elan_multiplier elan_multiplier[] = {
+ {1000, 0x02, 0x18},
+ {2000, 0x02, 0x10},
+ {4000, 0x02, 0x08},
+ {8000, 0x00, 0x00},
+ {16000, 0x00, 0x02},
+ {33000, 0x00, 0x04},
+ {66000, 0x01, 0x04},
+ {99000, 0x01, 0x05}
+};
+
+static struct cpufreq_frequency_table elanfreq_table[] = {
+ {0, 0, 1000},
+ {0, 1, 2000},
+ {0, 2, 4000},
+ {0, 3, 8000},
+ {0, 4, 16000},
+ {0, 5, 33000},
+ {0, 6, 66000},
+ {0, 7, 99000},
+ {0, 0, CPUFREQ_TABLE_END},
+};
+
+
+/**
+ * elanfreq_get_cpu_frequency: determine current cpu speed
+ *
+ * Finds out at which frequency the CPU of the Elan SOC runs
+ * at the moment. Frequencies from 1 to 33 MHz are generated
+ * the normal way, 66 and 99 MHz are called "Hyperspeed Mode"
+ * and have the rest of the chip running with 33 MHz.
+ */
+
+static unsigned int elanfreq_get_cpu_frequency(unsigned int cpu)
+{
+ u8 clockspeed_reg; /* Clock Speed Register */
+
+ local_irq_disable();
+ outb_p(0x80, REG_CSCIR);
+ clockspeed_reg = inb_p(REG_CSCDR);
+ local_irq_enable();
+
+ if ((clockspeed_reg & 0xE0) == 0xE0)
+ return 0;
+
+ /* Are we in CPU clock multiplied mode (66/99 MHz)? */
+ if ((clockspeed_reg & 0xE0) == 0xC0) {
+ if ((clockspeed_reg & 0x01) == 0)
+ return 66000;
+ else
+ return 99000;
+ }
+
+ /* 33 MHz is not 32 MHz... */
+ if ((clockspeed_reg & 0xE0) == 0xA0)
+ return 33000;
+
+ return (1<<((clockspeed_reg & 0xE0) >> 5)) * 1000;
+}
+
+
+static int elanfreq_target(struct cpufreq_policy *policy,
+ unsigned int state)
+{
+ /*
+ * Access to the Elan's internal registers is indexed via
+ * 0x22: Chip Setup & Control Register Index Register (CSCI)
+ * 0x23: Chip Setup & Control Register Data Register (CSCD)
+ *
+ */
+
+ /*
+ * 0x40 is the Power Management Unit's Force Mode Register.
+ * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency)
+ */
+
+ local_irq_disable();
+ outb_p(0x40, REG_CSCIR); /* Disable hyperspeed mode */
+ outb_p(0x00, REG_CSCDR);
+ local_irq_enable(); /* wait till internal pipelines and */
+ udelay(1000); /* buffers have cleaned up */
+
+ local_irq_disable();
+
+ /* now, set the CPU clock speed register (0x80) */
+ outb_p(0x80, REG_CSCIR);
+ outb_p(elan_multiplier[state].val80h, REG_CSCDR);
+
+ /* now, the hyperspeed bit in PMU Force Mode Register (0x40) */
+ outb_p(0x40, REG_CSCIR);
+ outb_p(elan_multiplier[state].val40h, REG_CSCDR);
+ udelay(10000);
+ local_irq_enable();
+
+ return 0;
+}
+/*
+ * Module init and exit code
+ */
+
+static int elanfreq_cpu_init(struct cpufreq_policy *policy)
+{
+ struct cpuinfo_x86 *c = &cpu_data(0);
+ struct cpufreq_frequency_table *pos;
+
+ /* capability check */
+ if ((c->x86_vendor != X86_VENDOR_AMD) ||
+ (c->x86 != 4) || (c->x86_model != 10))
+ return -ENODEV;
+
+ /* max freq */
+ if (!max_freq)
+ max_freq = elanfreq_get_cpu_frequency(0);
+
+ /* table init */
+ cpufreq_for_each_entry(pos, elanfreq_table)
+ if (pos->frequency > max_freq)
+ pos->frequency = CPUFREQ_ENTRY_INVALID;
+
+ policy->freq_table = elanfreq_table;
+ return 0;
+}
+
+
+#ifndef MODULE
+/**
+ * elanfreq_setup - elanfreq command line parameter parsing
+ *
+ * elanfreq command line parameter. Use:
+ * elanfreq=66000
+ * to set the maximum CPU frequency to 66 MHz. Note that in
+ * case you do not give this boot parameter, the maximum
+ * frequency will fall back to _current_ CPU frequency which
+ * might be lower. If you build this as a module, use the
+ * max_freq module parameter instead.
+ */
+static int __init elanfreq_setup(char *str)
+{
+ max_freq = simple_strtoul(str, &str, 0);
+ pr_warn("You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n");
+ return 1;
+}
+__setup("elanfreq=", elanfreq_setup);
+#endif
+
+
+static struct cpufreq_driver elanfreq_driver = {
+ .get = elanfreq_get_cpu_frequency,
+ .flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = elanfreq_target,
+ .init = elanfreq_cpu_init,
+ .name = "elanfreq",
+ .attr = cpufreq_generic_attr,
+};
+
+static const struct x86_cpu_id elan_id[] = {
+ X86_MATCH_VENDOR_FAM_MODEL(AMD, 4, 10, NULL),
+ {}
+};
+MODULE_DEVICE_TABLE(x86cpu, elan_id);
+
+static int __init elanfreq_init(void)
+{
+ if (!x86_match_cpu(elan_id))
+ return -ENODEV;
+ return cpufreq_register_driver(&elanfreq_driver);
+}
+
+
+static void __exit elanfreq_exit(void)
+{
+ cpufreq_unregister_driver(&elanfreq_driver);
+}
+
+
+module_param(max_freq, int, 0444);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, "
+ "Sven Geggus <sven@geggus.net>");
+MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs");
+
+module_init(elanfreq_init);
+module_exit(elanfreq_exit);